Sole structure and baseball spike shoes with the sole structure

ABSTRACT

A lower surface of an outsole is provided with a high traction stud and a low traction stud arranged around the high traction stud in a lateral side area located on a lateral side of a forefoot including a second proximal phalanx and a second metatarsal and third to fifth phalanges and metatarsals. Each of the high and low traction studs is configured to be longer in a direction along a stress direction, which is a direction of shear stress generated in the lateral side area in a follow through of a hitting movement, than in a direction orthogonal to the stress direction.

CROSS-REFERENCE TO RELATED APPLICATION

This application claims priority to Japanese Patent Application No. 2016-216298 filed on Nov. 4, 2016, the entire disclosure of which is incorporated by reference herein.

BACKGROUND

The present disclosure relates to a sole structure and baseball spike shoes with the sole structure, and more particularly relates to a sole structure of baseball spike shoes suitable for a baseball hitting movement and baseball spike shoes with the sole structure.

Sole structures such as those disclosed in, e.g., Japanese Unexamined Patent Publication No. H09-173104 have been suggested as a sole structure for baseball spike shoes.

Japanese Unexamined Patent Publication No. H09-173104 discloses a sole structure of a baseball spike shoe which has, on its outsole bottom surface, a toe portion projection, a thenar portion projection, a stepping portion projection, a hypothenar portion projection, a heel medial side projection, a heel anterior projection, a heel posterior projection, and a heel lateral side projection. In this sole structure, the position and orientation of each of the projections are determined so that the shoes have good anti-slide properties (i.e., traction properties) during various movements in baseball games, such as batting, throwing, fielding, and running.

SUMMARY

Various researches show that in general, in the case of a batter in the right-handed batter's box, a movement of the batter from the contact point of a bat with a ball (i.e., so-called “impact”) in the course of a swing of the bat, with the batter's left foot stepping forward on the ground, to the natural ending of the swing (i.e., so-called “follow through”) produces great pressure in a lateral side of the forefoot of the batter's left foot (hereinafter referred to as a “lead foot”) stepping forward on the ground. It has been desired to reduce this pressure transmitted from the lead foot after the impact to avoid the inhibition of a motion rotating about the center of the heel of the batter's lead foot to the lateral side of the foot (hereinafter referred to as a “rotational motion”) and allow the batter to have a full swing of the bat.

However, in the sole structure disclosed in Japanese Unexamined Patent Publication No. H09-173104, the position and orientation of each of the projections are determined to maximize the traction with respect to the feet of the batter during various movements in baseball games. Thus, too much traction is applied to the feet of the batter, which on the other hand causes unnecessarily high friction between the lead foot and the ground after the impact, resulting in transmitting the pressure to the lead foot. As a result, the pressure turns to a load on the lead foot, which is a cause of the inhibition of the rotational motion of the lead foot in the follow through.

In the sole structure disclosed in Japanese Unexamined Patent Publication No. H09-173104, the position and orientation of each of the projections are determined so that the traction is maximized in all the movements in baseball gages. Thus, the rotational motion of the lead foot is inhibited particularly in the follow through of a hitting movement, so that the batter cannot have a full swing of the bat. In other words, the sole structure disclosed in Japanese Unexamined Patent Publication No. H09-173104 does not always give optimal traction to the feet of the batter in the baseball hitting movement.

In view of the foregoing background, one or more aspects of the present disclosure are directed to a sole structure capable of giving optimal traction to a foot of a batter in a baseball hitting movement.

Specifically, a sole structure according to the present disclosure and baseball spike shoes with the sole structure make an improvement to the positions, materials, and shapes of studs provided on the outsole, thereby making it possible to give optimal traction in a baseball hitting movement.

Specifically, a first aspect of the disclosure is directed to a sole structure of baseball spike shoes worn by a wearer in a baseball hitting movement. The sole structure includes an outsole which supports a plantar of the wearer extending from a forefoot to a hindfoot. A lower surface of the outsole is provided with a plurality of studs which protrude downward and are arranged dispersedly in a lateral side area located on a lateral side of the forefoot including a second proximal phalanx and a second metatarsal and third to fifth phalanges and metatarsals. The plurality of studs include a high traction stud providing high traction, and at least one low traction stud arranged around the high traction stud and providing lower traction than the high traction stud. Each of the high and low traction studs is configured to be longer in a direction along a stress direction, which is a direction of shear stress generated in the lateral side area in a follow through of the hitting movement, than in a direction orthogonal to the stress direction.

According to the first aspect, each of the high and low traction studs arranged in the lateral side area is configured to be longer in a direction along a stress direction, which is a direction of shear stress generated in the lateral side area in a follow through of a hitting movement, than in a direction orthogonal to the stress direction. In other words, according to the first aspect, the traction studs are oriented along the stress direction so as not to work against the shear stress generated in the lateral side area in the follow through of a hitting movement. Thus, according to the first aspect, unnecessarily high friction is not generated between the lead foot of the batter and the ground after the impact, which avoids the inhibition of the rotational motion of the lead foot of the batter in the follow through. That is, according to the first aspect, the pressure is less likely to be generated in the lateral side of the forefoot of the batter's lead foot, which allows for a smooth rotational motion of the lead foot in the follow through. As a result, the batter may have a full swing of the bat. Moreover, the arrangement of a plurality of studs comprised of the high and low traction studs in the lateral side area ensures predetermined traction properties in the lateral side area. Thus, the sole structure according to the first aspect is capable of giving optimal traction to the foot of the batter in the baseball hitting movement.

A second aspect of the disclosure is an embodiment of the first aspect. In the second aspect, the at least one low traction stud includes a first low traction stud disposed on at least one of a front side or a back side of the high traction stud and spaced apart from the high traction stud.

According to the second aspect, the first low traction stud disposed on at least one of the front side or the back side of the high traction stud and spaced apart from the high traction stud may balance the traction in the longitudinal direction in the lateral side area together with the high traction stud.

A third aspect of the disclosure is an embodiment of the second aspect. In the third aspect, the first low traction stud is disposed on each of the front side and the back side of the high traction stud.

According to the third aspect, the first low traction studs arranged on the front and back sides of the high traction stud in the lateral side area may further balance the traction in the longitudinal direction in the lateral side area together with the high traction stud.

A fourth aspect of the disclosure is an embodiment of the second aspect. In the fourth aspect, the first low traction stud is made of thermoplastic polyurethane.

According to the fourth aspect, the first low traction stud made of thermoplastic polyurethane may reduce degradation of the first low traction stud with time, due to high resistance to wear of the thermoplastic polyurethane.

A fifth aspect of the disclosure is an embodiment of the first aspect. In the fifth aspect, the at least one low traction stud includes a second low traction stud disposed on a medial side of the high traction stud and spaced apart from the high traction stud.

According to the fifth aspect, the second low traction stud, together with the high traction stud, may provide appropriate traction in the lateral side area, and may also prevent the plantar from sinking in some area of the lateral side area in the foot width direction to keep the plantar approximately flat on the sole structure.

A sixth aspect of the present disclosure is directed to baseball spike shoes with the sole structure of the first to fifth aspects.

According to the sixth aspect, baseball spike shoes which are as advantageous as those in the first to fifth aspects may be obtained.

As can be seen from the foregoing description, the present disclosure may allow for a smooth rotational motion of the lead foot of a batter in the follow through of the hitting movement, which, as a result, enables the batter to have a full swing of the bat. Moreover, optimal traction may be given to the batter's foot particularly in a baseball hitting movement by the high and low traction studs ensuring predetermined traction in the lateral side area.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a diagram illustrating a plan view of a sole structure according to an embodiment of the present disclosure.

FIG. 2 is a diagram illustrating a perspective view of the entire sole structure, as viewed from the bottom.

FIG. 3 is a diagram illustrating a bottom view of the sole structure.

FIG. 4 is a diagram illustrating a bottom view of the sole structure with a human foot structure layered thereon.

FIG. 5 is a diagram illustrating a cross-sectional view taken along the line V-V in FIG. 3.

FIG. 6 shows foot stress distribution and a shear stress distribution diagram indicating directions of the shear stress in a hitting movement of a right-handed batter.

FIG. 7 is a partially-enlarged diagram illustrating a lateral side area X shown in FIG. 3.

DETAILED DESCRIPTION

An embodiment of the present disclosure will now be described in detail with reference to the drawings. Note that the following description of the embodiment is merely an example in nature, and is not intended to limit the scope, application, or uses of the present disclosure.

FIGS. 1 to 3 are diagrams illustrating an entire sole structure 1 according to an embodiment of the present disclosure. The sole structure 1 supports the plantar of a wearer (i.e., a batter in baseball games). A pair of shoes including the sole structure 1 and a shoe upper (not shown) provided on the sole structure 1 may be used as baseball spike shoes particularly suitable for a baseball hitting movement.

The drawings show the sole structure 1 for a left shoe only. A sole structure 1 for a right shoe is symmetrical to the sole structure 1 for the left shoe. In the following description, only the sole structure 1 for the left shoe will be described and the description of the sole structure 1 for the right shoe will be omitted. In the following description, the expressions “above,” “upward,” “on a/the top of,” “below,” “under,” and “downward,” represent the vertical positional relationship between respective components of the sole structure 1. The expressions “front,” “fore,” “forward,” “anterior,” “back,” “hind,” “behind,” “backward,” and “posterior” represent the positional relationship in the longitudinal direction between respective components of the sole structure 1. The expressions “medial side” and “lateral side” represent the positional relationship in the foot width direction between respective components of the sole structure 1.

As illustrated in FIGS. 1 to 4, the sole structure 1 includes an outsole 2 which supports the entire plantar from a forefoot F to a hindfoot H. The outsole 2 is made, for example, of a resin material including a thermoplastic resin such as polyamide-based resin (e.g., nylon, a registered trademark), polyurethane (PU), nylon-based elastomer, and so on, or of a rubber material including synthetic rubber, natural rubber, and so on. The outsole 2 has a shape of a thin plate.

The outsole 2 has, on its lower surface, an integrally-formed reinforcing rib 3 positioned at approximately the middle in the foot width direction and protruding downward. The reinforcing rib 3 extends from a posterior portion of the forefoot F to the hindfoot H. The reinforcing rib 3 increases the flexural rigidity of the outsole 2 from the posterior portion of the forefoot F to the hindfoot H.

The outsole 2 has, on its lower surface, a plurality of integrally-formed bases 12, 23, . . . , protruding downward. High traction studs 10 a to 10 f, which will be described later, are fixedly attached to the respective bases 12. Each of the bases 12 has approximately a triangular shape, as viewed from the bottom. First low traction studs 21 a to 21 g, which will be described later, are fixedly attached to the respective bases 23. Each of the bases 23 has approximately a triangular shape, as viewed from the bottom. As illustrated in FIG. 5, each base 23 is provided with grooves 24, 24 recessed upward from a lower surface of the base 23.

As illustrated in FIGS. 1 and 2, the sole structure 1 includes a midsole 4 which supports an area of the plantar from approximately a middle of the forefoot F in the longitudinal direction to the hindfoot H. The midsole 4 is made of a soft elastic material. Non-limiting suitable examples of the material for the midsole 6 include thermoplastic synthetic resins such as ethylene-vinyl acetate copolymer (EVA) and foams of the thermoplastic synthetic resins, thermosetting resins such as polyurethane (PU) and foams of the thermosetting resins, and rubber materials such as butadiene rubber and chloroprene rubber and foams of the rubber materials. A shoe upper (not shown) covering the wearer's foot is attached to peripheral portions of the outsole 2 and the midsole 4.

As illustrated in FIGS. 1 to 4, the outsole 2 has, on its lower surface, a plurality of downwardly-protruding studs arranged dispersedly. The plurality of studs include high traction studs 10 a to 10 f having high traction properties (i.e., anti-slide properties) and low traction studs 20, 20, . . . , arranged around each of the high traction studs 10 a to 10 f and having lower traction properties than the high traction studs 10 a to 10 f.

Each of the high traction studs 10 a to 10 f is made, for example, of a metal material which is relatively lightweight, resistant to wear, and tough, such as steel, aluminium alloy, titanium alloy, etc., or ceramics. Further, each of the high traction studs 10 a to 10 f is in a plate-like shape protruding downward from the lower surface of the outsole 2.

Specifically, as illustrated in FIG. 5, each of the high traction studs 10 a to 10 f has approximately an L-shaped cross-section, and includes flat plate portions 11, 11 orthogonal to each other. A holding portion 13 made of a material having greater hardness than the material of the outsole 2 is embedded in each base 12 of the outsole 2. In this embodiment, Shore D hardness of the outsole 2 is 63 D, and Shore D hardness of the holding portion 13 is 69 D. Each of the high traction studs 10 a to 10 f is fixedly attached to the outsole 2 such that one of the flat plate portions 11 is held by the holding portion 13 and the base 12, and that the other flat plate portion 11 protrudes downward from the holding portion 13 and the base 12.

The orientations of the high traction studs 10 a to 10 c are determined such that the shoes for both feet of the batter have increased grip with the ground in a movement from the beginning of a swing of the bat to a contact moment with a ball (i.e., a swing movement). As illustrated in FIG. 4, the high traction stud 10 a is arranged at a position corresponding to the second distal phalanx DP2 of the foot. The high traction stud 10 b is arranged at a position corresponding to the first proximal phalanx PP1 of the foot. The high traction stud 10 c is arranged at a position corresponding to a posterior portion of the first metatarsal MT1 of the foot.

The orientations of the high traction studs 10 d and 10 e are determined such that a shoe for the lead foot of the batter (the left foot in the case of a right-handed batter) has increased grip with the ground. As illustrated in FIG. 4, the high traction stud 10 d is arranged at a position corresponding to a medial side of the heel bone HL of the foot, whereas the high traction stud 10 e is arranged at a position corresponding to a lateral side of the heel bone HL of the foot. The position of the high traction stud 10 f will be described later.

As illustrated in FIGS. 2 to 4, some of the low traction studs 20, 20, . . . , are configured as the first low traction studs 21 a to 21 g. Each of the first low traction studs 21 a to 21 g is made, for example, of a resin material having high resistance to wear, such as thermoplastic polyurethane. Further, each of the first low traction studs 21 a to 21 g has a lower surface having approximately a triangular outer shape, as viewed from the bottom. The cross section of each of the first low traction studs 21 a to 21 g is tapered from approximately a middle portion in the vertical direction to a bottom end (see FIG. 5). In particular, each of the first low traction studs 21 f and 21 g has a lower surface having approximately an isosceles triangular outer shape, as viewed from the bottom.

As illustrated in FIG. 5, each of the first low traction studs 21 f and 21 g has, on its top portion, projections 22, 22 projecting upward in a cross-sectional view. Each of the first low traction studs 21 f and 21 g is fixedly attached to the base 23 with the projections 22 fitted in the grooves 24, 24 formed in the base 23, and is configured such that a portion extending from approximately a middle portion in the vertical direction to the bottom end protrudes downward from the base 23. The first low traction studs 21 a to 21 e are configured similarly to the first low traction studs 21 f and 21 g.

As illustrated in FIGS. 2 to 4, the first low traction stud 21 a is intended to balance the height from the ground in the foot width direction in relation to the first low traction studs 21 f and 21 g arranged in the lateral side area X. Specifically, the first low traction stud 21 a is arranged at a position corresponding to an anterior portion of the first metatarsal MT1 of the foot.

Each of the first low traction studs 21 b to 21 e is intended to balance the height from the ground in the foot width direction in an area from the midfoot M to the hindfoot H. Further, each of the first low traction studs 21 b to 21 e has a lower surface (i.e., a ground surface) having a larger area than the area of the lower surface of each of the first low traction studs 21 f and 21 g.

As illustrated in FIG. 4, the first low traction stud 21 b is arranged at a position corresponding to a navicular bone NB of the foot. The first low traction stud 21 c is arranged at a position corresponding to a medial side of a posterior portion of the heel bone HL of the foot. The first low traction stud 21 d is arranged at a position corresponding to a lateral side of the posterior portion of the heel bone HL of the foot. The first low traction stud 21 e is arranged at a position corresponding to a posterior end portion of the fifth metatarsal MT5 and a lateral side of the cuboid bone CB of the foot. The positions of the first low traction studs 21 g and 21 f will be described later.

As illustrated in FIGS. 2 to 4, the high and low traction studs 10 f, 20, . . . , are arranged dispersedly in the lateral side area X of the lower surface of the outsole 2. The lateral side area X is positioned at a lateral side of the forefoot F which includes the second proximal phalanx PP2, the second metatarsal MT2, and the third to fifth phalanges and metatarsals MT3 to MT5 of the foot. The term “phalange” used herein is a collective term referring to parts of foot bones including a proximal phalanx PP, a middle phalanx IP, and a distal phalanx DP of the foot.

Each of the high and low traction studs 10 f, 20, . . . , arranged in the lateral side area X is configured to be longer in a direction along a stress direction, which is a direction of shear stress S generated in the lateral side area X in the follow through of a hitting movement (see FIG. 6), than in a direction orthogonal to the stress direction. Note that FIG. 6 shows a shear stress distribution diagram related to a baseball hitting movement, and illustrates an area (see the broken line in FIG. 6) on which the shear stress S, which is necessary to prevent sliding between the sole structure 1 (the outsole 2) and the ground in the hitting movement, acts, and a direction of the shear stress S (i.e., the stress direction).

As illustrated in FIGS. 2 and 3, the high traction stud 10 f is disposed in the lateral side area X near the edge of the lateral side of the outsole 2. Specifically, as illustrated in FIG. 4, the high traction stud 10 f is arranged at a position corresponding to the fourth to fifth proximal phalanxes PP4 to PP5 of the foot.

The high traction stud 10 f is elongated generally in a direction toward the front and from the medial side to the lateral side, as viewed from the bottom. Specifically, as illustrated in FIG. 7, the high traction stud 10 f is configured such that a line segment L1 (see the broken line in FIG. 7) corresponding to a long side of the rectangular outer shape of the lower surface, as viewed from the bottom, extends in the direction of the shear stress S (i.e., the stress direction) generated at the position of the high traction stud 10 f as shown in FIG. 6. For example, suppose that there is an imaginary arc A with a radius corresponding to a distance between a rotational center point O, which is a position corresponding to the heel of the foot as viewed from the bottom, and a point R1, which is the center of the lower surface of the high traction stud 10 f (i.e., the center of the rectangle), as illustrated in FIGS. 3 and 7. The high traction stud 10 f is elongated such that the line segment L1 is rotated 24 degrees counterclockwise about the point R1 from a tangent a of the imaginary arc A. Note that as illustrated in FIG. 4, the rotational center point O is positioned at approximately the center of the heel bone HL (i.e., the heel) in the longitudinal and width directions of the foot as viewed from the bottom.

The first low traction studs 21 g and 21 f are arranged on the front and back sides of the high traction stud 10 f, respectively, in the lateral side area X. Specifically, as illustrated in FIG. 4, the first low traction stud 21 g is arranged at a position corresponding to the third middle phalanx IP3 of the foot. The first low traction stud 21 f is arranged at a position corresponding to the fifth metatarsal MT5 of the foot.

The first low traction stud 21 g is elongated generally in a direction toward the front side and from the medial side to the lateral side. Specifically, as illustrated in FIG. 7, the first low traction stud 21 g is configured such that a perpendicular bisector L2 (see the broken line in FIG. 7) of the base of approximately the isosceles triangular outer shape of the lower surface, as viewed from the bottom, extends in the direction of the shear stress S (i.e., the stress direction) generated at the position of the first low traction stud 21 g as shown in FIG. 6. For example, suppose that there is an imaginary arc B with a radius corresponding to a distance between the rotational center point O and a point R2, which corresponds to the inner center of approximately the isosceles triangular outer shape of the lower surface of the first low traction stud 21 g, as illustrated in FIGS. 3 and 7. The first low traction stud 21 g is elongated such that the line segment L2 is rotated 30 degrees counterclockwise about the point R2 from a tangent b of the imaginary arc B.

The first low traction stud 21 f is elongated generally in a direction toward the back side and from the medial side to the lateral side. Specifically, as illustrated in FIG. 7, the first low traction stud 21 f is configured such that a perpendicular bisector L3 (see the broken line in FIG. 7) of the base of approximately the isosceles triangular outer shape of the lower surface, as viewed from the bottom, extends in the direction of the shear stress S (i.e., the stress direction) generated at the position of the first low traction stud 21 f as shown in FIG. 6. For example, suppose that there is an imaginary arc C with a radius corresponding to a distance between the rotational center point O and a point R3, which corresponds to the inner center of approximately the isosceles triangular outer shape of the lower surface of the first low traction stud 21 f, as illustrated in FIGS. 3 and 7. The first low traction stud 21 f is elongated such that the line segment L3 is rotated 10 degrees counterclockwise about the point R3 from a tangent c of the imaginary arc C.

A second low traction stud 25 is also provided in the lateral side area X, as illustrated in FIGS. 2 and 3. The second low traction stud 25 is arranged on the medial side of the high traction stud 10 f, and is spaced apart from the high traction stud 10 f. The second low traction stud 25 is configured as one of the low traction studs 20. Specifically, as illustrated in FIG. 4, the second low traction stud 25 is arranged at a position corresponding to anterior end portions of the second to third metatarsals MT2 and MT3 of the foot. The second low traction stud 25 is made, for example, of the same material as the material of the outsole 2, and is integrally formed with the outsole 2 and protrudes downward from the lower surface of the outsole 2. The second low traction stud 25 has a lower surface having approximately a rectangular outer shape, as viewed from the bottom.

Similarly to the high traction stud 10 f, the second low traction stud 25 is elongated generally in a direction toward the front side and from the medial side to the lateral side. Specifically, as illustrated in FIG. 7, the second low traction stud 25 is configured such that a line segment L4 (see the broken line in FIG. 7) corresponding to a long side of the rectangular outer shape of the lower surface, as viewed from the bottom, extends in the direction of the shear stress S (i.e., the stress direction) generated at the position of the second low traction stud 25 as shown in FIG. 6. For example, suppose that there is an imaginary arc D with a radius corresponding to a distance between the rotational center point O and a point R4, which is the center of the second low traction stud 25 (i.e., the center of the rectangle), as illustrated in FIGS. 3 and 7. The second low traction stud 25 is elongated such that the line segment L4 is rotated 13 degrees counterclockwise about the point R4 from a tangent d of the imaginary arc D.

Note that the above degrees of angles are non-limiting examples of the orientations of the high and low traction studs 10 f, 21 f, 21 g, and 25 arranged in the lateral side area X. That is, preferably, each of the high and low traction studs 10 f, 21 f, 21 g, and 25 is elongated in the directions rotated 0 to 30 degrees counterclockwise about a point of the stud corresponding to the center of the lower surface of the stud (i.e., the center of gravity) from the respective one of the tangents a to d of the imaginary arcs A to D. Within this range, the high and low traction studs 10 f, 21 f, 21 g, and 25 may be oriented along the directions of the shear stress S (i.e., the stress direction) generated at the respective studs' positions as shown in the stress distribution diagram (see FIG. 6).

Advantages of Embodiment

Various researches show that in general, in the case of a batter in the right-handed batter's box, a movement of a batter from the contact point of a bat with a ball (i.e., impact) in the course of a swing of the bat, with the batter's left foot stepping forward on the ground, to the natural ending of the swing (i.e., the follow through) produces great pressure in a lateral side of the forefoot F of the batter's left foot (i.e., the lead foot) stepping forward on the ground. Reducing this pressure transmitted from the lead foot after the impact may avoid the inhibition of a motion rotating about the center of the heel of the batter's lead foot to the lateral side of the foot (i.e., a rotational motion) and allow the batter to have a full swing of the bat.

In the sole structure 1 according to the present embodiment, each of the high and low traction studs 10 f, 20, . . . (10 f, 21 f, 21 g, 25), arranged in the lateral side area X is configured to be longer in the direction along the stress direction, which is a direction of shear stress S generated in the lateral side area X in the follow through of a hitting movement, than in the direction orthogonal to the stress direction. In other words, in the sole structure 1 according to the present embodiment, the high and low traction studs 10 f, 20, . . . , arranged in the lateral side area X are oriented along the stress direction so as not to work against the respective shear stress S generated in the lateral side area X in the follow through of the hitting movement. Thus, the the sole structure 1 does not cause unnecessarily high friction between the lead foot of the batter and the ground after the impact, which avoids inhibition of the rotational motion of the lead foot of the batter in the follow through. That is, with the sole structure 1, the pressure is less likely to be generated in the lateral side of the forefoot F of the batter's lead foot, which allows for a smooth rotational motion of the lead foot in the follow through. As a result, the batter may have a full swing of the bat. Moreover, the arrangement of a plurality of studs comprised of the high and low traction studs 10 f, 20, . . . , in the lateral side area X ensures predetermined traction properties in the lateral side area X. Thus, the sole structure 1 according to the present embodiment is capable of giving optimal traction to the foot of the batter in the baseball hitting movement.

The first low traction studs 21 g and 21 f arranged on the front and back sides of the high traction stud 10 f in the lateral side area X may balance the traction in the longitudinal direction of the lateral side area X together with the high traction stud 10 f.

The first low traction studs 21 f and 21 g made of thermoplastic polyurethane may reduce the degradation of the first low traction studs 21 f and 21 g with time, due to high resistance to wear of the thermoplastic polyurethane.

The low traction studs 20 include the second low traction stud 25 arranged on the medial side of the high traction stud 10 f and spaced apart from the high traction stud 10 f. The second low traction stud 25, together with the high traction stud 10 f, may provide appropriate traction in the lateral side area X, and may also prevent the plantar from sinking in some portion of the lateral side area X in the foot width direction to keep the plantar approximately flat on the sole structure 1.

Other Embodiments

In the sole structure 1 according to the present embodiment, each of the first low traction studs 21 a to 21 g is made of thermoplastic polyurethane, but this is a non-limiting example. For example, each of the first low traction studs 21 a to 21 g may be made of synthetic rubber, natural rubber, or any other materials having resistance to wear. Alternatively, each of the first low traction studs 21 a to 21 g may be integrally formed with the outsole 2 and may be made of the same material as the material of the outsole 2 (i.e., polyamide-based resin). In this case, although the first low traction studs 21 a to 21 g are less resistant to wear because the polyamide-based resin is less resistant to wear than the thermoplastic polyurethane disclosed in the above embodiment, the outsole 2 and the integrally-formed first low traction studs 21 a to 21 g may achieve improved productivity and lightweight of the sole structure 1

In the sole structure 1 according to the present embodiment, the shapes of the high traction stud 10 f, the first low traction studs 21 f and 21 g, and the second low traction stud 25 arranged in the lateral side area X are not limited to those disclosed in the above embodiment. That is, the high and low traction studs 10 f, 20, . . . , arranged in the lateral side area X may have any shapes as long as the studs are configured to be longer in the direction along the stress direction, which is a direction of the shear stress S generated in the lateral side area X in the follow through of a hitting movement, than in the direction orthogonal to the stress direction.

The sole structure 1 according to the embodiment described above is configured such that the high traction stud 10 f is arranged in the lateral side area X at a position corresponding to the fourth to fifth proximal phalanxes PP4 to PP5, but this is a non-limiting example. The high traction stud 10 f may be arranged at any positions in the lateral side area X.

The sole structure 1 according to the embodiment described above is configured such that the first low traction studs 21 f and 21 g and the second low traction stud 25 are arranged around the high traction stud 10 f in the lateral side area X, but this is a non-limiting example. For example, the first low traction stud 21 f or 21 g alone may be arranged around the high traction stud 10 f. Alternatively, only the second low traction stud 25 may be arranged around the high traction stud 10 f. In short, it is suitable that at least one of the low traction studs 20 is arranged around the high traction stud 10 f in the lateral side area X.

Note that the present disclosure is not limited to the embodiments described above, and various changes and modifications may be made without departing from the scope of the present disclosure.

The present disclosure is industrially usable as a sole structure of baseball spike shoes suitable for a baseball hitting movement and as baseball spike shoes with the sole structure. 

What is claimed is:
 1. A sole structure of baseball spike shoes worn by a wearer in a baseball hitting movement, the sole structure comprising: an outsole which supports a plantar of the wearer extending from a forefoot to a hindfoot, wherein a lower surface of the outsole is provided with a plurality of studs which protrude downward and are arranged dispersedly in a lateral side area located on a lateral side of the forefoot including a second proximal phalanx and a second metatarsal and third to fifth phalanges and metatarsals, the plurality of studs includes a high traction stud providing high traction, and at least one low traction stud arranged around the high traction stud and providing lower traction than the high traction stud, and each of the high and low traction studs is configured to be longer in a direction along a stress direction, which is a direction of shear stress generated in the lateral side area in a follow through of the hitting movement, than in a direction orthogonal to the stress direction.
 2. The sole structure of claim 1, wherein the at least one low traction stud includes a first low traction stud disposed on at least one of a front side or a back side of the high traction stud and spaced apart from the high traction stud.
 3. The sole structure of claim 2, wherein the first low traction stud is disposed on each of the front side and the back side of the high traction stud.
 4. The sole structure of claim 2, wherein the first low traction stud is made of thermoplastic polyurethane.
 5. The sole structure of claim 1, wherein the at least one low traction stud includes a second low traction stud disposed on a medial side of the high traction stud and spaced apart from the high traction stud.
 6. Baseball spike shoes comprising the sole structure of claim
 1. 7. Baseball spike shoes comprising the sole structure of claim
 2. 8. Baseball spike shoes comprising the sole structure of claim
 3. 9. Baseball spike shoes comprising the sole structure of claim
 4. 10. Baseball spike shoes comprising the sole structure of claim
 5. 